Gas transmission companies today offer a balanced approach to meeting the growing demands in the U.S. for clean-burning natural gas while supporting, developing and utilizing various programs that enhance environmental compliance and minimize waste. Part of this strategy is to make sure that little, and preferably no, gas is lost in the thousands of miles of pipelines that run across the American continent. And by making sure that the pipeline surveillance equipment is running properly and at the highest possible performance, thousands of dollars can be saved daily.
Background
One company that has optimized its operation through the use of gas flowmeters is located in the Western U.S. The service provider delivers gas to more than nine million customers through a pipeline with a total capacity of more than 1.7 billion cubic feet per day. The line, which is more than 1,000 miles long, encompasses several compressor stations, receipt meter stations where the gas volumes entering the pipeline are measured, and more than 50 delivery meter stations measuring the gas volumes delivered from the pipeline. To efficiently run a gas line like this requires several flowmeters strategically located along the line. In this case, a mix of permanently installed and transportable clamp-on flowmeters is used: Clamp-on nonintrusive ultrasonic flowmeters provide the main control systems with flow rate data, while the transportable version is frequently relocated from site to site, fulfilling the need to verify and check the performance of the permanently installed instruments.
The flowmeters play a crucial role in what is considered one of the most sophisticated computer networks in the natural gas transportation industry. From the fully automated, real-time pipeline gas control center, operators can see exactly what is flowing through the pipeline at the exact time it is flowing.
The challenge
Prior to installing the meters, the gas company struggled with pipeline performance. Discrepancies between the receipt and delivery metering stations were found and since the company did not have portable meters at hand for verification purposes, they were not able to determine exactly what caused these apparent misreadings.
Rather than spending money and time on troubleshooting the entire system, it was decided to future-proof it instead with clamp-on ultrasonic flowmeters. The main reason for this decision was that the sensors can be clamped on to the outside of the pipes to eliminate the need to stop the flow and to cut the pipe, which results in lost revenue and additional installation costs.
Benefits of ultrasonic clamp-on gas flowmeters
Ultrasonic clamp-on flowmeters offer many advantages in capabilities and application versatility from high-performance to ease-of-installation and from availability of single-, dual- and four-beam configurations to a selection of IP65 (NEMA 4X), IP65 (NEMA 7) compact and IP65 (NEMA 7) wall-mount enclosures as well as transportable and dedicated versions.
Ultrasonic gas flowmeters are well-suited for applications that require:
- High precision
- Tolerance of wet gas
- High reliability combined with low maintenance
- High turndown ratio
- Low cost of installation and ownership
- Application diagnostics
- No pressure drop
- Insensitivity to pressure control valve noise
The solution
After discussing the options with a flowmeter supplier representative, the gas company executives and operation managers decided to go with a mix of clamp-on ultrasonic dedicated and portable flowmeters.
The dedicated meters were strategically located at the inlet, compressor, delivery and outlet stations to feed the control center with constantly updated and accurate flow data. By comparing this day-to-day, real-time data, the operators get an exact picture of the pipeline performance, making discrepancy and measurement issue detection quicker and more effortless. This solution offered a tremendous improvement compared to the company’s previous system and more commonly used applications featuring orifice plates and displacement transmitters coupled with a flow computer.
To supplement the dedicated meters, a number of transportable clamp-on ultrasonic meters were included as an integral part of the installation. Transportable flowmeters easily accommodate the growing need for check metering and validation tests required in the industry to maintain proper performance documentation for various management and regulatory bodies.
By including transportable meters in the complete package, the gas company now has a system that not only ensures easy and cost-efficient installation, accurate operation and optimized performance, but it also enables fast detection and troubleshooting of system inconsistencies. This makes the system valuable in terms of minimizing product and revenue losses as well as lowering the probabilities of encountering environmentally hazardous issues.
Jack Roushey is the product marketing manager in Siemens Process Instrumentation for magnetic flow and clamp-on ultrasonic flow. With 40 years of experience in the process measurement and instrumentation industry, he has held roles in product marketing, sales management, sales support and sales support operation management. Within Roushey’s current role, he is responsible for all strategic development, product marketing and product management issues associated with the magnetic and clamp-on flow products. He brings with him a wealth of instrumentation business development and extensive flow experience.
